There is no point during the jump when energy is zero. Before the jump itself the jumper builds up energy in his approach, or run. Energy and momentum are conserved as the jumper moves through the air. At the take off work is being done then momentum carries the jumper through the air. At the instant the jumper jumps into the air there is both potential and kinetic energy. As the jumper moves through the air approaching the maximum point of his jump potential energy becomes greater and kinetic energy becomes smaller. As the jumper approaches the ground again potential energy becomes smaller as kinetic energy becomes greater. The most important thing to remember is throughout the entire jump mechanical energy remains the same to to conservation of energy.
Energy:
There is no point during the jump when energy is zero. Before the jump itself the jumper builds up energy in his approach, or run. Energy and momentum are conserved as the jumper moves through the air. At the take off work is being done then momentum carries the jumper through the air. At the instant the jumper jumps into the air there is both potential and kinetic energy. As the jumper moves through the air approaching the maximum point of his jump potential energy becomes greater and kinetic energy becomes smaller. As the jumper approaches the ground again potential energy becomes smaller as kinetic energy becomes greater. The most important thing to remember is throughout the entire jump mechanical energy remains the same to to conservation of energy.